Bacillus Subtilis Vector Engineering for High D-Psicose-3-Epimerase

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Solution Overview

Problem

Existing methods for producing D-psicose-3-epimerase in Bacillus subtilis strains are not suitable for industrial application due to low enzyme activity and do not comply with safety and environmental regulations.

Innovation Solution

Development of an optimized Bacillus subtilis strain with inactivated alanine racemase (alrA) gene, sporulation (yqfD) gene, and erythromycin resistance (EmR-comK) gene cassette, combined with an optimized vector and fermentation medium, to enhance D-psicose-3-epimerase expression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional Bacillus subtilis strains are used for D-psicose-3-epimerase production, then the production process is simple, but the enzyme activity is low and does not comply with safety regulations

Engineering Contradiction:

Improveenzyme activityVSAvoidstrain modification complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The strain modification is divided into discrete functional segments: (1) inactivation of alrA gene for D-alanine deficiency, (2) inactivation of yqfD gene for sporulation deficiency, (3) integration of expression vector with optimized promoter and ribosome binding site. Each segment addresses a specific requirement independently, allowing modular assembly of the final strain.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The host cell strain is pre-modified with specific gene inactivations (alrA and yqfD) before introducing the expression vector. This preliminary preparation ensures that the strain has the necessary metabolic deficiencies and safety characteristics in place before the enzyme production system is installed.

Inventive Principle:

Principle #10Preliminary action

2Quantity of substance

If conventional expression vectors are used, then the vector construction is simple, but the D-psicose-3-epimerase expression level is low

Engineering Contradiction:

Improveenzyme production levelVSAvoidvector optimization complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The expression vector is optimized by changing key parameters: (1) promoter strength and specificity, (2) ribosome binding site sequence and accessibility, (3) operon structure and transcriptional control. These parameter modifications collectively enhance the transcriptional and translational efficiency of the D-psicose-3-epimerase gene.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The optimized expression vector acts as an intermediary carrier that bridges the D-psicose-3-epimerase gene and the host cell machinery. It provides enhanced transcriptional and translational control elements that mediate high-level enzyme production while maintaining plasmid stability and replicability in the modified Bacillus subtilis strain.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the strain includes multiple gene inactivations for safety and selection, then safety and selection are improved, but the strain construction complexity increases

Engineering Contradiction:

Improvesafety complianceVSAvoidstrain construction ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Multiple functional requirements are merged into a single integrated strain construction approach: (1) D-alanine deficiency (alrA inactivation) serves as both a safety marker and a selection mechanism, (2) sporulation deficiency (yqfD inactivation) provides safety by preventing spore formation, (3) the expression vector integration combines expression function with strain stability. These merged functions are achieved through coordinated gene inactivations and vector integration in a single strain development process.

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The optimized strain and vector system enable high D-psicose-3-epimerase production, suitable for industrial use, while adhering to safety and environmental regulations.

Implementation Method 1

a genetically modified Bacillus subtilis strain wherein the alanine racemase alrA gene is inactivated

Methodology Applied

Scientific EffectGene inactivation:

Implementation Method 2

an optimized vector, mainly for producing a D-psicose 3-epimerase

Methodology Applied

Scientific EffectGene expression:

Implementation Method 3

interconversion between D-fructose and D-psicose by epimerization using the enzymes named D-psicose 3-epimerases

Methodology Applied

Scientific EffectEnzyme catalysis: Enzyme

Implementation Method 4

a method for producing a D-psicose 3-epimerase, mainly by a fermentation process

Methodology Applied

Scientific EffectFermentation: Fermentation

Data Source

PatentUS12595473B2Genetically modified bacillus subtilis strain, optimized vectors, and uses thereof

Publication Date: 2026.04.07 ROQUETTE FRERES SA

AI summary

A genetically modified Bacillus subtilis strain has been transformed with an optimized vector, mainly for producing a D-psicose 3-epimerase.